Bistable pneumatic flip flop apparatus

ABSTRACT

A pressure switching and venting pneumatic control valve for use wherever reciprocating motion is desired. The pressure control and venting apparatus controls pressure actuating fluid and venting for a mechanism having a reciprocating part to be moved in opposite directions and to be stopped. There is a shuttle having a pair of interconnected, oppositely arranged pistons operated by venting or relief of fluid pressure in the pneumatic system, and there is a simple remote control means for the control valve.

United States Patent Reid [ BISTABLE PNEUMATIC FLIP FLOP 1 May 23,1972

Primary Examiner-Henry T. Klinksiek APPARATUS Attorney-4. C. Baisch [72] Inventor: John D. Reid, Monrovia, Calif. 57 ABSTRACT ASSigHeeI Hamilton p y, Whittier, Calif- A pressure switching and venting pneumatic control valve for Filed June 16 1970 use wherever reciprocating motion is desired. The pressure control and venting apparatus controls pressure actuating [21 Appl. No.: 46,691 fluid and venting for a mechanism having a reciprocating part to be moved in opposite directions and to be stopped. There is a shuttle having a pair of interconnected, oppositely arranged Cl 137/596.2 pistons operated by venting or relief of fluid pressure in the [51 1 Int. Cl r ..Fl6k 11/10 pneumatic t m, and there is a simple remote control means [58] Field of Search 1 37/596. l 8, 596.2, 625.66 f th ontr l valve.

5 References Cited v 9 Claim, 7 Drawing Figures UNITED STATES PATENTS 2,674,266 4/1954 Gardner ..137/625.66

Z4 2 52 we I90 /o2 10 9 3 m0 u h 95 U a 1 /04 70 m8 l8 %7z /4 /Z 83 a :5 5 /0 8g l6 2 llt k T 58 \T'-'\ 48 seam t\\\ BISTABLE PNEUMATIC FLIPFLOP APPARATUS BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION There is a shuttle comprising a pair of opposed pistons having piston valves controlling respective vent ports. A central air supply pressurizes one or the other of the air passages or conduits to the cylinder of a pneumatically operated actuator, depending on the position of the shuttle. With the shuttle positioned to pressurize one of the air passages, one of the pistons is positioned outwardly to permit pressure air to enter said one air passage, the piston valve of said one piston being closed.

1 The opposite or other'piston is then bottomed with its piston valve open. In order to switch the pressurization to the other air passage, a pressure relief or vent valve in the circuit of the pressurized passage is opened. The pistons of the shuttle then reverse positions and pressure air is supplied to the other air passage, while the piston valve of the just vented air circuit is opened and serves to vent air from the actuator so as to permit the reciprocating actuator member or piston to be actuated by pressure air on one side, the other side being vented through the open piston valve. Venting the now pressurized part of the air circuit effects reverse movement of the actuator piston. The valve is thus a bistable pneumatic flip flop.

The control valve may be manually or automatically controlled.

BRIEF DESCRIPTION OF THE DRAWINGS Referring to the drawings, which are for illustrative pur' poses only:

FIG. I is a schematic sectional view of a pressure control valve embodying the present invention;

FIG. 2 is an end view of the valve assembly;

FIG. 3 is a sectional view taken on line 33 of FIG. 2;

FIG. 4 is a sectional view taken on line 4-4 of FIG. 3.

FIG. 5 is a sectional view taken on line 55 of FIG. 3;

FIG. 6 is a side elevational view of the pressure control valve operably connected with an actuator having a reciprocating piston, the valve being controlled in one part of its cycle of operation by the piston of the actuator; and

FIG. 7 is a similar view of an alternative arrangement.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to Hg. 1 of the drawings, there is shown, schematically, a pressure control valve embodying the present invention, having a valve body 10 with shuttle cylinders 12 and 14 at each side separated by a partition or partition wall 16. Shuttle cylinders 12 and 14 are axially aligned and their inner ends are connected together by an axial bore 18.

There is an air supply passage having one end connected to the bore 18 intermediate the ends of said bore andadapted to be connected with a source of air under pressure, not shown, by means of a conduit 22.

From the inner ends of the shuttle cylinders there extends operating or actuating air passages 24 and 26, respectively, which are adapted to be connected with the respective ends of an air cylinder 30, FIGS. 6 and 7, by means of conduits 32 and 34, respectively. Velocity adjustment means is provided for the passages 24 and 26, and as shown said velocity adjustment means comprises respective tapered velocity adjustment valves 35 which are operably disposed in similarly tapered bores 35a. At their outer ends the valves 35 are externally threaded, as at 35b, for threadable disposition in tapped outer end parts of said bores 35a. Adjustment valves 35 have inner end portions that extend across the passages 24 and 26 and the outer ends of said velocity adjustment valves have slots 35c for reception of tools for rotating said valves 35 to vary the effective size of said passages 24 and 26. 7

There are also relief or vent passages 36 and 38 which extend from the inner ends of said shuttle cylinders for relieving the pressure at the inner ends of the shuttle cylinders by selectively venting same to atmosphere by pressure relief means. This pressure relief means comprises normally closed vent valves, indicated generally at 40 and 42, respectively, at the ends of vent conduits 44 and 46 which have ends connected with said vent passage, the valves 40 and 42 being at the outer ends of said conduits. Vent valves 40 and 42 have valve members 48 and 50 with respective valve stems 52 and 54, said valve members 48 and 50 seat on valve seats 56 and 58, respectively, and said valves are yieldingly urged closed by means of springs 60 provided therefor and which react between the bottom walls of respective spring retaining recesses and respective spring retainers 62 at the free ends of the valve stems 52 and 54. While the vent valves 40 and 42 are shown at the ends of the vent conduits 44 and 46, it is to be understood that said valves may be at the ends of the vent passages 36 and 38, or otherwise operably located. It is also to be understood that other types of relief valves may be used, such as tire valves 66, for example, as shown in FIG. 3.

Shuttle cylinders 12 and 14 have respective pistons 70 and 72 of a shuttle, indicated generally at 74, said pistons being of a plastic or other suitable material, such as aluminum, stainless steel or the like, and said pistons being connected together by a shuttle rod 76, which is operably disposed in the bore 18 and is somewhat smaller in diameter than said bore. End portions of said shuttle rod are threaded, as at 78, and threadably disposed in tapped bores provided therefor in the inner ends of the respective pistons. At the inner end of each of the threaded portions 78 there is a shoulder against which the inner ends of the shuttle pistons seat so that the pistons are spaced apart at a predetermined distance, which is greater than the thickness of the wall 16, so that when the inner end of one shuttle piston engages or seats against the adjacent side of said wall 16 the inner end of the other piston is spaced from the adjacent side of said wall 16, as best shown in FIGS. 1 and 2.

At their inner ends the shuttle pistons have reduced diameter parts 80 and 82 to provide annular areas 84 and 86, respectively, for the flow of air when the shuttle pistons are seated against the respective adjacent sides of the wall 16, said areas then communicating with the respective passages 24 and 26, as well as the respective passages 36 and 38.

There are annular piston seals or rings 88 disposed in annular grooves provided therefor in the shuttle pistons 70 and 72. These piston seals may be O-rings of well known character.

Shuttle pistons have bores 90 and 92 which extend inwardly from their outer ends. These bores are offset from the axis of the respective shuttle pistons and extend but part way through said pistons, the inner-ends of said bores being tapered inwardly to provide valve seats for piston valves 94 and 96 for the respective shuttle pistons 70 and 72, said valve seats being in walls at the inner ends of said bores 90 and 92.

Inwardly of the walls having the valve seats are respective chambers 100 and 102 which are connected with said bores 90 and 92 by axial openings in said walls. The inner ends of said chambers 100 and 102 are defined by walls having openings therethrough in axial alignment with the respective bores 90 and 92.

The piston or pressure relief valves 94 and 96have' valve stems 104 and 106, respectively, which extend through the axial openings in the walls at the outer and inner ends of said chambers 100 and 102, said openings in said wallsbeing of somewhat greater diameter than the diameter of said valve stems so that air may pass through said openings and into the bores 90 and 92 and, hence, to the atmosphere. In other words, there are atmospheric vents which are controlled by said piston valves 94 and 96.

Secured on each valve stem is a flange or washer 108, or the like, and there is a spring 110 and 1 12 on the valve stems 104 and 106 reacting between said flange 108 and the walls defining the outer ends of respective chambers 100 and 102 for yieldingly urging the piston valves closed.

When the pistons 70 and 72 of the shuttle 74 are equally spaced from the wall 16, that is when the shuttle is centered,

the inner free ends of the valve stems 104 and 106 are closely adjacent to the wall 16 separating the cylinders and 14, but said inner ends of said valve stems are slightly spaced from said wall 16. As soon as one or the other of the shuttle pistons move inwardly, the stem of its valve engages wall 16 and, upon further inward movement of said piston, the valve of said piston is opened. While said piston moves inwardly, there is venting of air from the pressurized side of the system, as described hereinafter.

While the above-described pressure control valve may be used wherever reciprocating motion is desired, an example of one type of installation is for controlling a pneumatic actuator, indicated generally at 120, which includes the air cylinder 30 in which a reciprocating actuator piston 31 operates, said piston having a piston rod 122.

When the present pressure control valve is connected to the cylinder 30 and to a source of air under pressure, it controls the pressurizing and venting of the ports of the air cylinder 30 in appropriate sequence, it being assumed that the arm 125 on piston rod 122 is not used. 7

Air from a suitable source of air under pressure enters the valve by way of the conduit 22, passage 20, through the space between the shuttle rod 76 and the wall of the bore 18, and thence to the inner ends of the cylinders 12 and 14. Depending on the position of the shuttle, air under pressure pressurizes one or the other of the ports at the ends of the air cylinder 30. As shown in FIG. 1, the shuttle piston 74 is in its leftward operating position, its vent valve being closed. Air under pressure which has entered the inner end of cylinder 12 and has been transmitted to the air cylinder by way of the passage 24 and conduit 32 has moved the actuator piston 31 in cylinder 30 upwardly, the upper end of said cylinder having been vented by way of conduit 34, passage 26, and the piston valve 96 which was opened when the piston 72 started to move inwardly in its cylinder. When the shuttle piston 72 has bottomed, that is when its inner end has abutted against the wall 16, the annular area serves as an air connection between the passage 86 and the passage 38. It is to be understood that the above-described part of the cycle of operation was initiated by opening the vent valve 42, said valve closing once this part of the cycle is initiated.

To reverse the direction of movement of the piston 31 in the cylinder 30 it is necessary to vent the pressurized side. This is effected by opening the vent valve 40. As shown in Flg. 1, the vent valves 40 and 42 are actuated manually, although one or the other or both may be actuated automatically.

When vent valve 40 is opened the pressure on piston 70 is reduced and a pressure difference develops which moves the shuttle to the right, as viewed in FIG. 1. It has been found that such shifting of the shuttle is aided by piston valve spring 112 of the outwardly moving piston 72. When the shifting of the shuttle is in the opposite direction, the spring 110 of the piston valve 94 aids in shifting of the shuttle. These piston valve springs are effective in aiding the shifting of the shuttle in respective directions from the extreme outward position to the centered position. The piston valve in piston 70 is then opened as soon as said piston 70 passes inwardly beyond its centered position and the inner or free end of its stem 104 engages the wall 16. Opening of piston valve 94 effects venting of the lower cylinder port. At the same time that the shuttle moves to the right and the piston 72 moves outwardly to and beyond its centered position, the piston valve 96 closes allowing the upper end of the cylinder to be pressurized, air below actuator piston 31 in said cylinder 30 being vented to the atmosphere. When the piston 31 in cylinder 30 reaches its lower limit of movement it stops.

Referring to FIG. 6, the arm or traveling block is secured on the piston rod 122 and is adapted to open the vent valve 42 when said piston in cylinder 30 reaches the end of its downward movement, thus automatically initiating the upward part of its cycle. When it reaches the upper end of its movement said piston stops. With this arrangement one full cycle is effected each time the push-button 126 at the free end of the valve stem 52 of the vent valve 40 is pushed or actuated.

Referring to FIG. 7, the arm or block 125 is secured to the piston rod 122 between the vent valves 40 and 42 which are spaced apart and so positioned that the arm 125 will engage the respective vent valves to alternately open same when the piston 31 comes to the lower and upper ends of its stroke. Thus, once the cycling of the actuator is started it will automatically continue until the source of pressure air is shut off by means of a valve, not shown. When the pressure air is supplied to the pressure control valve the cycling is started or resumed and automatically continued.

The invention and its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of the parts of the invention without departing from the spirit and scope thereof or sacrificing its material advantages, the arrangement hereinbefore described being merely by way of example, and I do not wish to be restricted to the specific form shown or uses mentioned, except as defined in the accompanying claims.

I claim:

1. A pressure control valve, comprising:

a body having axially aligned, oppositely arranged cylinders therein;

a partition separating said cylinders, and having a bore therethrough axially aligned with said cylinders. Said cylinders being adapted to be operably connected with a source of actuating fluid under pressure, each cylinder also having a vent fluid passage connection;

a normally closed vent valve for venting each vent fluid passage;

a shuttle comprising:

pistons in respective cylinders; rigid means extending through the .bore in said partition whereby said pistons have simultaneous movement in said cylinders and whereby as one piston moves outwardly, the other piston moves inwardly in the respective cylinders, said shuttle having a centered position whereat the respective pistons thereof are equally spaced from the inner ends of their respective cylinders;

a normally closed pressure relief piston valves for the relief of pressure of the respective actuating fluid passages, each of said piston valves having a part for engagement with said piston when said piston moves inwardly of its cylinder beyond its position when the shuttle is centered for opening such valve the other piston valve being closed with such outward movement of the other piston, such shuttle being actuated by a differential of pressures on the pistons thereof.

2. The invention defined by claim 1, wherein said cylinders are axially aligned and disposed at opposite sides of said partition, said piston valves being carried by said pistons.

3. The invention defined by claim 2, wherein said pistons have air flow passage means from the inner ends to the exterior, and said piston valves control said air flow passage means, said piston valves comprising respective valve members and valve stems, said valve stems being of such length as to project from the inner ends of said pistons and be spaced from the adjacent sides of said partition when the shuttle is centered, inward movement of either piston causing the inner free end of its relief valve to engage the partition and be opened with further inward movement of such piston.

4. The invention defined by claim 3, wherein the inner ends of the respective actuating fluid passages communicate with the inner ends of the respective cylinders and an inner end portion of each piston is of reduced diameter to provide an area for a fluid connection between a vent passage and the inner end of the respective cylinders, the vent valves controlling venting of the respective vent passages.

5. The invention defined by claim 3, wherein said pressure relief piston valves have springs urging said valves closed, outward movement of a piston from a position inwardly of the centered position of the shuttle is aided by the spring of the pressure relief piston valve of said piston at least until the shuttle is substantially centered.

6. The invention defined by claim 1, including velocity adjustment valves for each of the actuating fluid pressure passages.

7. A pressure control valve comprising:

a body having axially aligned, oppositely arranged cylinders therein;

a partition between said cylinders and having a bore therethrough axially aligned with said cylinders, said bore having a passage adapted to be connected with a source of air under pressure, the inner ends of said cylinders having passages adapted to be connected with a source of actuating air under pressure;

vent passages for respective cylinders;

a shuttle comprising:

a piston in each said cylinders;

and a rigid rod of smaller diameter than the bore through said partition, said rod connecting the pistons together in fixed spaced relationship to each other, the spacing of said piston being greater than the thickness of said partition;

each of said pistons having a pressure relief connection between the inner end thereof and the outer end;

and normally closed pressure relief piston valves controlling respective relief connections, said pressure relief piston valves being yieldingly urged in the closing direction and having valve stems extending from the inner ends of said pistons, the inner free ends of said stems abutting the adjacent side of the partition upon inward movement of respective pistons inwardly of a centered position of the shuttle for opening the respective pressure relief piston valves;

and normally closed vent valves for venting respective vent passages.

8. The invention defined by claim 7, wherein said pressure relief pressure valves have spring means urging said valves closed and, when the shuttle shifts from one extreme position to the other, the spring of the relief valve of the piston at the inner end of its cylinder when the shifting begins aids in the shifting up to substantially the centered position of the shuttle.

9. A pressure control valve comprising:

a body having axially aligned, oppositely arranged cylinders therein;

a partition having a bore therethrough axially aligned with said cylinders, the inner ends of said cylinders being connected together by said axial bore through said partition, the inner end of each cylinder being connected with an actuating air supply passage adapted to be connected to a device having a reciprocating member whereby respective sides of said member may be subjected to actuating pressure and respective sides vented, said inner ends of said cylinders also having vent passages;

a normally closed vent valve for each vent passage;

and a shuttle comprising:

a shuttle piston operably disposed in each of said cylinders, said shuttle having a centered position and movable in both directions therefrom;

means extending through the bore in said partition connecting said shuttle pistons together in spaced relation for synchronious movement in both directions; said pistons being spaced apart a greater distance than the thickness of said partition; and normally closed piston relief valve means for each piston, each of said piston relief valve means being opened by action of its respective piston when its respective piston moves inwardly beyond the centered position of said shuttle. 

1. A pressure control valve, comprising: a body having axially aligned, oppositely arranged cylinders therein; a partition separating said cylinders, and having a bore therethrough axially aligned with said cylinders. Said cylinders being adapted to be operably connected with a source of actuating fluid under pressure, each cylinder also having a vent fluid passage connection; a normally closed vent valve for venting each vent fluid passage; a shuttle comprising: pistons in respective cylinders; rigid means extending through the bore in said partition whereby said pistons have simultaneous movement in said cylinders and whereby as one piston moves outwardly, the other piston moves inwardly in the respective cylinders, said shuttle having a centered position whereat the respective pistons thereof are equally spaced from the inner ends of their respective cylinders; a normally closed pressure relief piston valves for the relief of pressure of the respective actuating fluid passages, each of said piston valves having a part for engagement with said piston when said piston moves inwardly of its cylinder beyond its position when the shuttle is centered for opening such valve the other piston valve being closed with such outward movement of the other piston, such shuttle being actuated by a differential of pressures on the pistons thereof.
 2. The invention defined by claim 1, wherein said cylinders are axially aligned and disposed at opposite sides of said partition, said piston valves being carried by said pistons.
 3. The invention defined by claim 2, wherein said pistons have air flow passage means from the inner ends to the exterior, and said piston valves control said air flow passage means, said piston valves comprising respective valve members and valve stems, said valve stems being of such length as to project from the inner ends of said pistons and be spaced from the adjacent sides of said partition when the shuttle is centered, inward movement of either piston causing the inner free end of its relief valve to engage the partition and be opened with further inward movement of such piston.
 4. The invention defined by claim 3, wherein the inner ends of the respective actuating fluid passages communicate with the inner ends of the respective cylinders and an inner end portion of each piston is of reduced diameter to provide an area for a fluid connection between a vent passage and the inner end of the respective cylinders, the vent valves controlling venting of the respective vent passages.
 5. The invention defined by claim 3, wherein said pressure relief piston valves have springs urging said valves closed, outward movement of a piston from a position inwardly of the centered position of the shuttle is aided by the spring of the pressure relief piston valve of said piston at least until the shuttle is substantially centered.
 6. The invention defined by claim 1, including velocity adjustment valves for each of the actuating fluid pressure passages.
 7. A pressure control valve comprising: a body having axially aligned, oppositely arranged cylinders therein; a partition between said cylinders and having a bore therethrough axially aligned with said cylinders, said bore having a passage adapted to be connected with a source of air under pressure, the inner ends of said cylinders having passages adapted to be connected with a source of actuating air under pressure; vent passages for respective cylinders; a shuttle comprising: a piston in each said cylinders; and a rigid rod of smaller diameter than the bore through said partition, said rod connecting the pistons together in fixed spaced relationship to each other, the spacing of said piston being greater than the thickness of said partition; each of said pistons having a pressure relief connection between the inner end thereof and the outer end; and normally closed pressure relief piston valves controlling respective relief connections, said pressure relief piston valves being yieldingly urged in the closing direction and having valve stems extending from the inner ends of said pistons, the inner free ends of said stems abutting the adjacent side of the partition upon inward movement of respective pistons inwardly of a centered position of the shuttle for opening the respective pressure relief piston valves; and normally closed vent valves for venting respective vent passages.
 8. The invention defined by claim 7, wherein said pressure relief pressure valves have spring means urging said valves closed and, when the shuttle shifts from one extreme position to the other, the spring of the relief valve of the piston at the inner end of its cylinder when the shifting begins aids in the shifting up to substantially the centered position of the shuttle.
 9. A pressure control valve comprising: a body having axially aligned, oppositely arranged cylinders therein; a partition having a bore therethrough axially aligned with said cylinders, the inner ends of said cylinders being connected together by said axial bore through said partition, the inner end of each cylinder being connected with an actuating air supply passage adapted to be connected to a device having a reciprocating member whereby respective sides of said member may be subjected to actuating pressure and respective sides vented, said inner ends of said cylinders also having vent passages; a normally closed vent valve for each vent passage; and a shuttle comprising: a shuttle piston operably disposed in each of said cylinders, said shuttle having a centered position and movable in both directions therefrom; means extending through the bore in said partition connecting said shuttle pistons together in spaced relation for synchronious movement in both directions; said pistons being spaced apart a greater distance than the thickness of said partition; and normally closed piston relief valve means for each piston, each of said piston relief valve means being opened by action of its respective piston when its respective piston moves inwardly beyond the centered position of said shuttle. 